A) Progenitor cells in green. B) Progenitor cells in brown. C) Hair follicle that is rich with stem cell and progenitor cells (Source: George Cotsarelis, MD, University of Pennsylvania School of Medicine)

George
Cotsarelis, MD, study leader and chair of the Department of Dermatology at the
University of Pennsylvania School of Medicine, along with a team of
researchers, have discovered that the amount of stem cells on the scalp may
determine male pattern baldness.

Researchers
came to this conclusion after comparing samples from men who were going through
hair transplants. When looking at samples from both bald parts of the scalp and
non-bald parts of the scalp, both had the same number of stem cells.

"We
asked: 'Are stem cells depleted in bald scalp?'" said Cotsarelis. "We
were surprised to find the number of stem cells was the
same in the bald part of the scalp compared with other places, but did find a
difference in the abundance of a specific type of cell, thought to be a
progenitor cell. This implies that there is a problem in the activation of stem
cells converting to progenitor cells in bald scalp."

Cotsarelis
and his team of researchers studied their theory a little closer, and found
that hair follicles shrink rather than disappear in male pattern baldness. So
hair is available in bald spots of the scalp, but it's microscopic compared to
other non-balding parts due to the stem cells' problem with activation.

Cotsarelis
found similar results in 2007 while studying hair follicles in adult mice. He
discovered that “re-awakening” dormant genes in developing embryos could
regenerate hair follicles. They used wound healing in these models to
manipulate certain traits, and by stimulating these once-active genes; stem
cells formed new hair follicles.

Researchers
are unsure as to why stem cells refuse to convert into the progenitor cells to
maintain a certain amount of hair follicles, but they remain hopeful due to the
fact that both areas on the scalp have the same number of stem cells. That way,
they can find ways to stimulate stem cell conversion and re-grow the hair in
bald areas.

In
addition to this study, Cotsarelis and his team would like to study female
pattern baldness as well for comparison purposes. This could lead to a larger
understanding of why the hair shrinks in humans, and could lead to the
development of cell-based treatments for
male and possibly female pattern baldness.

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If you have pattern baldness (spreading from a spot on the top of your head) Rogain is 90+% effective. On the other hand, try having non-pattern baldness (spreading from the front of the hairline, back) at 26; short of doing restoration surgery there's no effective treatment.

My wife, who is actually younger than me, gets carded everywhere we go, whereas the same people smirk if I go to pull out my ID.

quote: This could lead to a larger understanding of why the hair shrinks in humans, and could lead to the development of cell-based treatments for male and possibly female pattern baldness.

I’m assuming this is your statement, in the article it clearly states:

quote: "We were surprised to find the number of stem cells was the same in the bald part of the scalp compared with other places, but did find a difference in the abundance of a specific type of cell, thought to be a progenitor cell.

The stem cells are there so cell based therapies would be useless. Now inducing differentiation is another story but that would not be cell based.

For some reason the researchers seem to be confused regarding the terms stem cell and progenitor cell. They describe a lack of "activation" (I assume they mean progression) of the stem cells for the hair loss. While progenitor can be used to imply a lineage relationship from a stem cell it is confusing since it usually implies the first or at least a node turning point with the remaining cells being descendants. I do not know if that confused terminology is truly from them or poor writing.

Failure of stem cell maturation makes sense since minoxidil is both a vasodilator as well as an activator of prostaglandin endoperoxide synthase (PGHS), either could affect stem cell progression (the latter more likely). On a side note if one has pattern baldness they should also minimize the use of NSAIDs as these are inhibitors of PGHS-1 (PGHS-2 is the inducible form) which has been shown to accelerate hair loss (possibly by targeting PGHS-1).